1. Field of the Invention
The present invention relates to a liquid crystal display, and in particular, to a reflective color liquid crystal display.
2. Description of the Related Art
A reflective liquid crystal display is known which displays images utilizing reflected light resulting from reflection of incident light by a reflective film formed on a back surface side of a liquid crystal. An example of the reflective liquid crystal display is a polymer network liquid crystal display (PNLCD) using polymer network liquid crystals (PNLCs). Unlike a display using normal liquid crystals, the PNLCD eliminates the need for a polarizing plate and thus enables bright reflective display.
For the PNLC, ultraviolet light is radiated to a solution containing photopolymerized precursors (monomers) mixed with liquid crystals to polymerize the monomers so that the liquid crystals are dispersed in the network of the resultant polymer. In a color PNLCD based on an active matrix scheme, for example, a color filter substrate (CF substrate) comprising a color filter and on which a reflective film is formed is disposed on the back side of a display surface, and a TFT substrate with TFTs (Thin Film Transistors) is disposed on the front side of the display surface.
Ultraviolet light is radiated to a cell in order to polymerize the monomers. However, when the reflective film is provided on the TFT substrate side, the ultraviolet light is radiated from the CF substrate side, and in this case, the color filter absorbs the ultraviolet light, disadvantageously preventing the monomers from being polymerized. Thus, the reflective film is formed on the CF substrate side and the TFT substrate is formed to be transmissive so that the monomers are polymerized by radiating ultraviolet light from the TFT substrate side.
However, disadvantageously, wiring lines around pixels on the TFT substrate may act to make the polymerization of the monomers near the wiring lines incomplete, reducing reflectance (scattering performance) and reliability. Another problem is that, since the CF substrate with the reflective film is disposed on the back side of the display surface, whereas the TFT substrate is disposed on the front side of the display surface, reflected light from the back surface of the TFT substrate may affect display performance (make the display garish) to significantly degrade visibility. Another problem is that areas in which the wiring lines and transistors are disposed are prevented from being utilized for display, aperture ratio may decrease.